An inexpensive, high-speed, multiple-section, computed-tomographic x-ray transmission scanner is under development. This scanner utilizes a novel multiple-ring target and a scanning electron beam source to achieve scan speeds as low as 25 msec. No mechanical motion is involved. By scanning each of four target rings in sequence, eight 1.2 cm thick dual-sections may be scanned in 100msec. Various scanning modes for blood flow studies, myocardial motion and thickening studies, ventricular volume changes, and high-resolution imaging will be available. A stationary crystal-photodiode detector ring will be used in combination with a fast, parallel computer data acquisition system. The key technical innovation is the development of a novel high-power electron accelerator and steering system that can scan a small stable, electron-beam-spot along a tungsten ring at high speed. The first two years of the project are devoted to the development of the physics and engineering feasibility using an experimental test bed facility. The system is designed to be competitive in cost and image quality with conventional (slow) scanners. The improved speed of an electronic scanner will dramatically extend the capabilities of non-invasive cardiac CT into important areas of diagnosis and quantitation of coronary heart disease.